battery AUDI A4 2000 B5 / 1.G Brakes OBD Workshop Manual

01-1


On Board Diagnostic (OBD)

On Board Diagnostic (OBD), basic
information

The control module of a system with OBD
detects malfunctions during vehicle operation
and stores them as Diagnostic Trouble Codes
(DTCs) in a permanent memory. The DTCs
remain intact in the memory if the power supply
from the battery is interrupted.
The OBD function relates to the electrical and
electronic parts of a system; in other words it
only registers malfunctions which have an effect
on the electric signals.
On Board Diagnostic (OBD) helps technicians
perform a more targeted diagnostic
troubleshooting. Use the VAG1551/1552 Scan
Tools (ST) or the VAS5051 tester to achieve the
potential offered by On Board Diagnostic (OBD).
To do this, the scan tool and the respective
control module must exchange data. They must
communicate with each other.
The Data Link Connector (DLC) is the interface
for communication between the control module
and the scan tool.
Troubleshooting is started by connecting the
scan tool to the Data Link Connector (DLC). This
establishes a data link between the control
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